Cylindrospermopsis raciborskii is from the group of interesting organisms that have characteristics of both simple plants and bacteria and are called cyanobacteria or blue-green algae. This ancient group of algae tolerates a wide range of environmental conditions and has even been found growing in hot springs, Antarctic lakes under permanent ice cover, and extremely salty pools. Some species form dormant cells that can withstand dry or harsh conditions for extended periods of time. A number of blue-green algae species release toxins that can cause death in mammals, birds, and fish and illness in humans.

Like others in this group, Cylindrospermopsis produces oxygen by photosynthesis and can fix nitrogen from the air and so can live without relying on nitrogen sources in the water. This particular species grows abundantly (blooms) in subtropical freshwater lakes and rivers with high levels of phosphorus and other nutrients. In recent years, this species has begun replacing other bloom-forming algae as the dominant alga following the nutrient enrichment of lakes, reservoirs, and rivers around the world and appears to be moving into more temperate climates. It has been found in Zimbabwe, Hungary, Thailand, Mexico, Australia, Brazil, and more recently in the southeastern United States. Surrounding states where Cylindrospermopsis has been found--but not in bloom condition--include Michigan, Illinois, and Ohio.

Blue-green algae can successfully compete against other groups of such as green algae and diatoms because they can store phosphorus for later use and are not preferred as food by zooplankton (microscopic animals), larval fish and other animals that graze on many kinds of algae. When blue-green algae dominate the aquatic community, they can become a nuisance by forming surface scums, producing obnoxious taste and odor compounds, and sometimes releasing toxic or irritating substances into the water.

Cylindrospermopsis is very small, even in comparison to other microscopic algae, and is made of a filament that is either linear or coiled and composed of rectangular cells with basal heterocysts (nitrogen fixing cells). Unlike many other blue-greens, it does not form scum at the water surface but does produce a brown tint to the water that cannot be easily distinguished from suspended sediment or other types of algae that appear brown, such as diatoms.

Cylindrospermopsis, when found in large quantities, can produce several substances that show toxicity in laboratory studies, including: (1) cylindrospermopsis, which is mainly toxic to the liver, but can affect the kidneys, heart and other organs, and may be carcinogenic and genotoxic; (2) saxitoxin, which is a neurotoxin that can cause paralytic fish poisoning leading to paralysis and respiratory distress in fish eaters; and (3) anatoxin-a, which is a neuromuscular agent that can result in paralysis, respiratory distress and convulsions. These and other toxins can also be produced by several other species of blue-green algae. Humans and animals are primarily exposed to toxic effects by drinking or swimming in untreated water.

How and when was Cylindrospermopsis discovered in Indiana?

Cylindrospermopsis was found blooming and producing toxin in Ball Lake, Steuben County, Indiana, in August of 2001. As a result of this find, a task force of agency, university, and private company representatives was assembled to discuss the implications. Shortly after the first meeting, a Purdue University professor, Dr. Carole Lembi, reviewed samples in early October that had been collected during the summer and preserved for later analysis from Eagle Creek Reservoir, Morse Reservoir and Kokomo Reservoir. These samples also contained moderate amounts of Cylindrospermopsis. The distribution of these findings suggests that other water bodies in Indiana may also be affected. The Indiana Department of Environmental Management (IDEM) has taken samples for further laboratory analysis to determine the current concentration of algae and the presence of any toxins.

In waters where Cylindrospermopsis has been identified, state agencies suggest that people, pets and livestock avoid swallowing water from these reservoirs or immediately downstream until results of laboratory analyses are available. Because the alga grows most rapidly in warm, sunny weather and during periods of little rainfall, the probability of finding the alga or its toxins would be very low during the winter months. Data that are currently available from a few Indiana lakes indicate that Cylindrospermopsis tends to bloom here in late summer (August to early September).

Where did this algal species come from?

The discovery of this organism blooming (growing abundantly) in a Midwestern lake was a surprise to most scientists since Cylindrospermopsis, originally found in Australia, Brazil, and more recently in Florida and North Carolina, was thought to be a subtropical organism. The species has been found more recently in several Midwestern states. Along with many other exotic and nuisance organisms, Cylindrospermopsis could potentially be spread by human or natural influences. Zebra mussels, Eurasian watermilfoil, fish diseases and other damaging species can be carried to new areas by anglers, boaters, shipment of pond plants and during other activities that transport water across distances. The decisions you make about discarding fish, water or aquatic plants are critical in slowing or preventing spread of nuisance species that can destroy fisheries and aquatic resources. How you discard unused bait fish, where you dump bilge water or water from your live well, where you dispose of live fish or fish parts, and what you do with plants from your pond or plants attached to your trailer or boat can affect the spread of unwanted species. Many of these problem species are too small to see in the water in your bait bucket or live well. Once these exotic nuisances are deposited in waters, it can be very difficult or impossible to remove them and reverse the negative impacts. Help prevent problems by never moving water or animals from one lake or river to another one.

What effects can Cylindrospermopsis have on human and animal health?

No human deaths from blue-green algae, including Cylindrospermopsis, have been reported in the United States. People exposed to blue-green algal blooms by swimming in affected lakes or rivers have experienced skin irritations, allergic reactions, gastrointestinal symptoms, and respiratory problems. Nausea, vomiting, and liver damage have been implicated after consumption of the blue-green toxin cylindrospermopsin in finished drinking water in Australia. Liver failure occurred in people in Brazil following an incident during which growth of a different blue-green algae (Microcystis sp.) produced toxins in water used for intravenous kidney dialysis. Most of the knowledge about the toxicity of these compounds, including dose-response interactions, comes from animal experiments. Because human toxicity from direct algal exposure has rarely been documented, there are no dose-response data or even experimental data in humans.

Several standard methods of treating drinking water are thought to remove these toxins, including use of activated carbon, oxidation with chlorine, ozone, and ultraviolet degradation with the addition of titanium dioxide. Questions remain regarding formation and health effects of byproducts of the treatment process.

Some people are more sensitive to chemicals causing allergic reactions or toxicity. In general, children, older people and individuals with sensitive immune systems may be more susceptible to these effects. Pets and livestock are more likely to drink large quantities of raw lake or river water, potentially resulting in negative health effects.

Is Cylindrospermopsis the only blue-green alga that can have health effects?

The toxic effects associated with Cylindrospermopsis are common to several other species of blue-green algae. There are more than 50 major types of freshwater blue-green algae, and about one-third of them can produce some form of toxins. Blue-green algae are a harmless, natural part of the water system in small numbers. But when they dominate the plant community, the algae can interfere with the ecological health and human use of the water by producing offensive taste and odor compounds and sometimes forming a thick scum on the surface. Decaying algae consume oxygen in the water, causing fish kills if oxygen levels drop too low. A scum of algae floating on the surface can shade out beneficial plants that provide habitat for fish and wildlife.

What are the symptoms of toxic effects of blue-green algae?

Symptoms of swallowing water with toxic amounts of substances produced by blue-green algae can include stomach or head aches, diarrhea, cough, respiratory distress, and eye or ear irritations. Similar symptoms can also be caused by swimming in and swallowing water that contains E. coli or other bacteria, viruses, and disease-causing microbes. Some other blue-green algae and tiny parasites that cause swimmer's itch can also produce a rash after contact with the water. Humans, pets or livestock could be similarly affected by toxins from blue-green algae. In rare cases, animals have been known to die from drinking water contaminated with toxins produced by blue-green algae.

Are fish caught from these waters safe to eat?

The toxins produced by freshwater blue-green algae do not appear to bioaccumulate in fish and other edible aquatic life in lakes and rivers to the degree that they can in some seafood. Toxic results from consumption of freshwater animals have not been documented. Anglers should always take a common sense approach to eating fish caught from lakes or rivers. If the fish looks or smells unhealthy or was dead when you found it, then don't eat it. If an angler is concerned, avoid lakes with heavy algal blooms.

Should I report illness in humans or pets after swimming in water?

There are no reported problems with human health effects of blue-green algae toxins in United States at this time. In the event someone suspects they may have become sick from exposure to toxins produced by blue-green algae, contact your family physician so that pertinent information can be relayed to the state department of health. If pets fall ill with the symptoms indicated above after swimming in or drinking from lakes or rivers, explain these circumstances to your veterinarian.

How can I tell if the water contains Cylindrospermopsis?

Where the state is aware of potential risks associated with blooms of this alga, local health departments and citizens will be notified through an advisory. The mouse bioassay is an established laboratory method to determine presence of some toxic substances in algae, and there are numerous other analytical methods for determining the kind and amount of chemicals found in algae-tainted water. Field testing kits for toxins are not yet available. Unlike several other blue-green algae, Cylindrospermopsis does not form a surface scum. Dense algal cells typically are located in a band several feet from the surface in a reservoir, lake or other slow moving or still water. These cells are extremely small and do not create a color in the water that would easily distinguish it from other algae. There is no taste or odor associated with Cylindrospermopsis or its toxins. Compounds, such as geosmin and MIB, that cause taste and odor problems in some Indiana drinking water supplies, are not thought to pose a health risk to humans and are not necessarily associated with blue-greens that may produce toxins. Allergic reactions to lake water, such as skin rashes, eye or ear irritation or a cough, are also not necessarily an indication of the presence of toxins. Therefore, it would be highly unlikely that the public could provide observations of local algae blooms that could be readily identified with this species.

Can the growth of Cylindrospermopsis be prevented or controlled?

Like any other plant, blue-green algae require light, nutrients, and heat to thrive. Physical disturbance, such as water currents or mixing, can also disrupt plants. Long-term control of algae and nuisance plants usually involves land management that prevents excessive soil erosion and runoff of sediment and nutrients. Factors that can produce excessive algal blooms include:

Runoff into waterways with nutrients (nitrogen and phosphorus) from land clearing and soil erosion, inadequate sewage and septic systems, agriculture fertilizers, industrial effluent, lawn fertilizers and waste from livestock, pets or wildlife.

Lack of flow in reservoirs or in pooled parts of rivers -- rain can flush algae from the system and disrupt its growth.

Warm, sunny weather provides both heat and light to stimulate algae growth. Warmer winters and an early spring thaw can increase plant abundance.

Clear water can also increase the depth to which light reaches and cause a larger band of algae to grow.

Drought years can cause an increase in abundance of algae and other aquatic plants by reducing sediment runoff and increasing penetration of light, as well as causing water bodies to be shallower and with lower flow than usual.

Several state and federal agencies in Indiana are working actively with local communities and landowners to improve land use management and protect water quality. If you are interested in participating in these efforts, please contact any of the following programs:

The benefits of better land management may take many years to improve water quality because resuspension of nutrients from lake sediments can continue to support growth of algae. Therefore, contingency methods that provide short-term control and drinking water treatment may be necessary. Where surface waters are used for recreation or watering of livestock and pets, application of chemicals that kill algae, such as copper sulfate, may temporarily control algal growth. Several standard methods of treating drinking water are thought to successfully remove toxins or reduce their concentration to a safe level.

Chemical treatment can be used to manage the growth of algae and release of the toxin at lower concentrations over a longer period of time rather than a sudden die-off of a large bloom. Determining the appropriate level and timing of treatment can be difficult. Although Cylindrospermopsis and other blue-greens may release some toxins during life cycle transitions, the toxins are primarily tied up in the cells while they are alive. Some algae are more “leaky” than others, but all types of toxin-producing algae tend to release most of their toxins when they die. Algae can naturally produce large blooms that can then die suddenly in a boom and bust cycle in the spring or late summer and fall. The timing of these cycles is related to climate, weather, water conditions, and species and can vary from year to year. While nervous system toxins degrade rapidly in the environment, some liver toxins may persist for an indeterminate time after the algal cells die. In Australia, human health effects were noticed when a blue-green algae bloom was treated with copper sulfate in a drinking water reservoir. Repeated treatment over time can complicate management by removing the competing forms of algae and leave Cylindrospermopsis as the dominant species. There is also some evidence that this species can become resistant to copper.

There are several ways to increase movement of the water in order to disrupt the growth of algae. In smaller bodies of water, aerators can pump air into deeper water and circulate it to the surface. Like other machines, aerators require maintenance and energy to operate. Blue-green algae growth can sometimes be reduced if water flow through a lake or reservoir can result in a nearly complete exchange of water every 5 to 10 days. In some reservoirs, this can be achieved by regulating release of water at the dam or siphoning water over the dam during dry periods. However, the resulting changes in water level may also have an adverse effect on other uses of the lake or reservoir.

What are state agencies and lake managers doing to address issues related to toxins

produced by blue-green algae, including Cylindrospermopsis?

Scientists from IDNR, IDEM, Indiana State Department of Health, U.S. EPA, Purdue University, Wright State University and water utility representatives are meeting in Indianapolis to determine the best protection of public health and the ecological system in state waters from Cylindrospermopsis. The EPA will test for toxins produced by some forms of blue-green algae at 200 public water systems considered vulnerable. Several water sources are in Indiana and Ohio. Monitoring the development of algal growth in relation to other factors, such as temperature and rainfall, can allow lake managers to predict and preempt the growth of algae. Determining a course of management that has the greatest potential for controlling toxin production with the least negative impact on other uses of the water can be complex.

Should I be concerned about contamination of blue-green algae sold as dietary supplements?

There is no standard for the harvesting of blue-green algae. An alga commonly sold as a dietary supplement, Spirulina, may be confused for or contaminated with a toxin-producing cyanobacterium. In 2000, the Oregon State Department of Health surveyed 87 commercially available products of blue-green algae and found that 85 of them (98 percent) were contaminated with potentially toxic compounds. Dietary supplements are exempt by law from Food and Drug Administration (FDA) regulation.

Additional resources

Much of the information in this fact sheet was based on information from the EPA in Cincinnati, a number of other websites, and from a website by Dr. Thomas Morris, Medical Epidemiologist, North Carolina Harmful Algal Blooms Program. Microscope images of the toxic algae, Cylindrospermopsis, can be found at the Purdue University, Botany Dept. website.